Existing centre body burners for gas turbines have an injection lance with 12 fingers and with two nozzles on each finger. An example from EP 2725303 is shown in FIG. 1, showing a reheat burner arrangement 100 with a centre body 101 in a cross-sectional view. The leading edge area of each streamlined body 300 has a profile wherein, with reference to a central plane 302 of the streamlined bodies 300, the leading edges are provided with at least one lobe 303, or at least two complementary lobes. The surface curvature of the lobes 303 run in conjunction with each other in the same direction. The traverse or quasi-traverse deflections from the central plane of two adjacent streamlined bodies (300), which form the lobes 303, are in alignment with each other.
FIG. 2 shows another reheat burner arrangement 100 from EP 2725303 in a cross-sectional view. The leading edge area of each streamlined body 400 has a profile wherein, with reference to a central plane 403 of the streamlined bodies 400, the leading edges are provided with at least one lobe 401, 402, or at least two complementary lobes, in opposite transverse directions 404, 405. The traverse deflection from the central plane of two adjacent streamlined bodies 400 which form the lobes 401, 402 are inverted in that the transition from a planar leading edge region to the deflections is smooth with a surface curvature representing a function with a continuous first derivative.
These existing centre body burners for gas turbines show good performance in terms of emissions and OTDF/RTDF (overall temperature distribution factor/radial temperature distribution factor). However, it has been appreciated that the thermoacoustic pulsation level might not be negligible in these existing centre body burners and that improved designs would be advantageous.